A Strategy for the Synthesis of 1,2-Dichlorotetrafluorocyclobutene from Hexachlorobutadiene and Its Reaction Pathway

In this paper, a novel strategy for the preparation of 1,2-dichlorotetrafluorocyclobutene (DTB) was proposed via a catalytic gas-phase process of fluorination using hexachlorobutadiene (HCBD) and anhydrous HF. In order to search for suitable catalysts and reveal the reaction pathway for this synthetic route, a series of studies were carried out. First, CrO_<i>x</i>/ZnO catalysts with different promoters (Ni, Cu, In, Al) were prepared by a precipitate method and the optimum reaction conditions were investigated. The highest activity was achieved on the Cr–Ni–Zn catalyst, whose yield of DTB reached 90% by a multiple cycle reaction. Second, the effects of different promoters on the properties of catalysts were studied by Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), temperature-programmed desorption in ammonia (NH₃-TPD), and X-ray photoelectron spectroscopy (XPS). It was found that the Cr–Ni–Zn catalyst showed the excellent catalytic performances with more CrO_<i>x</i>F_<i>y</i> species, higher oxygen concentration, and widely distributed acid strength on its surface. Third, combining experimental results with theoretical calculations, a reaction pathway has been proposed. This study offers an economic synthetic route for DTB from HCBD, which is a valuable and promising method for industrial production

Metal Ion-Regulated Fluorescent Sensor Array Based on Gold Nanoclusters for Physiological Phosphate Sensing

The detection of physiological phosphates (PPs) is of great importance due to their essential roles in numerous biological processes, but the efficient detection of different PPs simultaneously remains challenging. In this work, we propose a fluorescence sensor array for detecting PPs based on metal-ion-regulated gold nanoclusters (AuNCs) via an indicator-displacement assay. Zn2+ and Eu3+ are selected to assemble with two different AuNCs, resulting in quenching or enhancing their fluorescence. Based on the competitive interaction of metal ions with AuNCs and PPs, the fluorescence of AuNCs will be recovered owing to the disassembly of AuNC-metal ion ensembles. Depending on different PPs’ distinct fluorescence responses, a four-channel sensor array was established. The array not only exhibits good discrimination capability for eight kinds of PPs (i.e., ATP, ADP, AMP, GTP, CTP, UTP, PPi, and Pi) via linear discriminant analysis but also enables quantitative detection of single phosphate (e.g., ATP) in the presence of interfering PPs mixtures. Moreover, potential application of the present sensor array for the discrimination of different PPs in real samples (e.g., cell lysates and serum) was successfully demonstrated with a good performance. This work illustrates the great potential of a metal ion-regulated sensor array as a new and efficient sensing platform for differential sensing of phosphates as well as other disease-related biomolecules

Point Defect Effects on Photoelectronic Properties of the Potential Metal-Free C₂N Photocatalysts: Insight from First-Principles Computations

Through first-principles computations on the structural, electronic, and optical properties of perfect and defective two-dimensional C₂N crystals, the effects of point defects on photoelectronic characteristics of this potential photocatalysts were investigated. The introduction of point defects, including N vacancies, interstitial C impurities, O@C and H@N dopants, and the interstitial O in the benzene ring and big ring, should result in more appropriate band structures and broadened optical absorptions and generally promoted carrier mobilities of C₂N photocatalysts. Remarkably, the defective C₂N with N vacancy, interstitial O in benzene/big ring, and interstitial C in benzene ring are highly recommended for the photocatalytic applications due to their broadened optical absorption, spatially separated e^––h⁺ pairs, excellent redox capacities, and fast carrier migrations. Our theoretical results can provide some guidance for further exploring the utilization of 2D C₂N material and some possible strategies for improving its photoactivities

Formaldehyde Decomposition from −20 °C to Room Temperature on a Mn–Mullite YMn₂O₅ Catalyst

Large ambient temperature changes (−20–>25 °C) bring great challenges to the purification of the indoor pollutant formaldehyde. Within such a large ambient temperature range, we herein report a manganese-based strategy, that is, a mullite catalyst (YMn2O5) + ozone, to efficiently remove the formaldehyde pollution. At −20 °C, the formaldehyde removal efficiency reaches 62% under the condition of 60,000 mL gcat–1 h–1. As the reaction temperature is increased to −5 °C, formaldehyde and ozone are completely converted into CO2, H2O, and O2, respectively. Such a remarkable performance was ascribed to the highly reactive oxygen species generated by ozone on the YMn2O5 surface based on the low temperature-programed desorption measurements. The in situ infrared spectra showed the intermediate product carboxyl group (−COOH) to be the key species. Based on the superior performance, we built a consumable-free air purifier equipped with mullite-coated ceramics. In the simulated indoor condition (25 °C and 30% relative humidity), the equipment can effectively decompose formaldehyde (150 m3 h–1) without producing secondary pollutants, rivaling a commercial removal efficiency. This work provides an air purification route based on the mullite catalyst + ozone to remove formaldehyde in an ambient temperature range (−20–>25 °C)